hey got a 1993 ford f-250 with a 351w. a week after i put headers on my truck I started to notice a knock in the engine. I have plenty of oil pressure and of course oil.I only hear the knock when I accelerate really fast other wise its not noticeable. also if if I start it i dont hear it at idle nor on the throttle if Im not in gear. any Ideas?

 

prolly an exhaust leak..the sound produced can mimic a knock..

 

also..did u check and retorque ur header bolts after a few miles?